I usually find that “obvious” reasoning is very often wrong, especially when politically contentious.
You could look at countries with higher rates of immigration (say my own country New Zealand at 30% immigrants, compared against Sweden with 20%, although NZ immigrants are often middle-class from culturally compatible English countries). Switzerland has 30% immigrants. https://wikipedia.org/wiki/List_of_sovereign_states_and_depe...
You can sometimes find good articles with facts that help define the point you are trying to make.
It not about the rate of immigration. If you immigrate a lot of high social economic status people then the amount of low social economic status citizen does not increase.
At the start of wars (or rather, the start of instability in a region) this actually occurs. The people who leave first is those with economical means to leave early, and those with higher education is generally those that tend to have an easier time to relocate successfully.
A other way to see this in economic terms is to look at the cities which took in a lot of immigrants. The first "wave" of immigrants did not increase the social costs that society had. It was only in the later waves that local budgets started to become strained from immigration and where the average tax revenue increase from immigration became significant less than the average increased costs per additional immigrant. An economic paper around 2017 tried and sadly failed to explain this in Swedish news, as it basically got labeled as being both anti and pro immigration.
For a very long time the majority of immigration to Sweden was from nearby Scandinavian countries. There is a lot of people moving between the borders simply because they got family on both sides, or get a job opportunity that happens to be on one side of a line on a map and well within driving distance.
People in Sweden however don't generally think of those people as immigrants, and their social economic status is average or maybe even a bit higher than average. Sweden also has about equal amount of swedes doing the same so the end result on the haves and the have-nots is basically static for that form of immigration.
Naturally, when people discuss immigration and immigration politics, immigration and emigration between Scandinavian countries are not part of the discussion and are generally exempted through specific treaties between the countries.
In New Zealand a lot of immigrants get residency via the skilled migrant category. They are generally well educated, well informed, and often reasonable well off. The skilled migrant category chooses those attributes, including a category if you are just wealthy enough! Current scoring system I think: https://rnz-ressh.cloudinary.com/image/upload/s--mt6iKVzS--/...
Also due to the number of applicants, I believe there is definitely a filter for the more capable immigrants. They might be poor, but they work hard and usually show us locals up (at least that is what I have seen). Many immigrants might not integrate well, but their kids are usually totally kiwi New Zealanders.
The same thing occurs for tradies going from NZ to the UK: it tends to be the focused hard working and highly skilled that emigrate from New Zealand.
You could look at countries with higher rates of immigration (say my own country New Zealand at 30% immigrants, compared against Sweden with 20%, although NZ immigrants are often middle-class from culturally compatible English countries). Switzerland has 30% immigrants. https://wikipedia.org/wiki/List_of_sovereign_states_and_depe...
You can sometimes find good articles with facts that help define the point you are trying to make.